1. Field
The present invention relates to the field of semiconductor processing and more particularly to a semiconductor device having doped epitaxial regions and its methods of fabrication.
2. Discussion of Related Art
Increasing the performance of semiconductor devices, in particular transistors, has always been a major consideration in the semiconductor industry. For example, during the design and fabrication of metal oxide semiconductor field effect transistors (MOSFETs), it has always been a common goal to increase the electron mobility of the channel region and to reduce the parasitic resistance to improve device performance.
Other methods of improving device performance include, for example, reducing the overall resistance of the MOSFET by doping the region between the source/drain regions and the channel region, which is referred to as the ‘tip’ or source/drain extension regions of the MOSFET. For example, a dopant is implanted in the source/drain regions and an annealing step diffuses the dopant towards the channel region. However, there are limits to controlling the dopant concentration and location. Furthermore, the implant and diffusion method does not address the issues of lateral undercut or parasitic resistance at the tip regions.